March 14th, 2011 by GarySchwitzer in News, Research
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Here we go again. Headlines across America blaring lines like, “Coffee may reduce stroke risk.”
It was a big study, but an observational study. Not a trial. Not an experiment. And, as we say so many times on this website that you could almost join along with the chorus, observational studies have inherent limitations that should always be mentioned in stories. They can’t prove cause and effect. They can show a strong statistical association, but they can’t prove cause and effect. So you can’t prove benefit or risk reduction. And stories should say that.
USA Today, for example, did not explain that in its story. Nor did it include any of the limitations that were included in, for example, a HealthDay story, which stated:
“The problem with this type of study is that there are too many factors unaccounted for and association does not prove causality, said Dr. Larry B. Goldstein, director of the Duke Stroke Center at Duke University Medical Center.
“Subjects were asked about their past coffee consumption in a questionnaire and then followed over time. There is no way to know if they changed their behavior,” Goldstein said.
And, he noted, there was no control for medication use or other potential but unmeasured factors.
“The study is restricted to a Scandinavian population, and it is not clear, even if there is a relationship, that it would be present in more diverse populations. I think that it can be concluded, at least in this population, that there was not an increased risk of stroke among coffee drinkers,” he said.”
When you don’t explain the limitations of observational studies — and/or when you imply that cause and effect has been established — you lose credibility with some readers. And you should. Read more »
*This blog post was originally published at Gary Schwitzer's HealthNewsReview Blog*
January 26th, 2011 by GarySchwitzer in Health Tips, Opinion
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The February issue of Prevention magazine has an article entitled “Surprising Faces of Heart Attack” profiling “three women (who) didn’t think they were at high risk. Their stories are proof that you could be in danger without even knowing it.” No, their stories are not proof of that.
The story is about three women in their 40s. The story varyingly states that the three should have had the following screening tests:
— Advanced cholesterol test, carotid intimal medial thickness test ( CIMT)
— Advanced cholesterol test and stress echocardiography
— Cardiac calcium scoring and CIMT
There’s an accompanying piece: “7 Tests You’re Not Having That Could Save Your Life.”
I asked one of our HealthNewsReview.org medical editors, Harold Demonaco, director of the Innovation Support Center at the Massachusetts General Hospital, to review the two pieces. As his day-job title suggests, he deals with review of the evidence for new and emerging healthcare technologies. He wrote:
The section “7 Tests you are not having that could save your life” states: “If you have not had these cutting edge screenings, put this magazine down and call your doctor. Now.”
Wow. While much of the information is correct, it is the context that is disturbing. Suggesting that these tests are essential in everyone is a bit over the top. Some of the information provided for each test is basically correct. However in some cases the recommendations go well beyond national guidelines.
The major issue here is the tacit assumption that tests are infallible, without any downsides and are always a good thing. That is simply not the case. So who should get these tests? Read more »
*This blog post was originally published at Gary Schwitzer's HealthNewsReview Blog*
September 3rd, 2010 by GarySchwitzer in Better Health Network, Health Policy, Health Tips, News, Opinion, Quackery Exposed, Research
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The September issue of Prevention magazine inaccurately headlines the story “4 Ways Coffee Cures.” There’s no solid proof that coffee cures anything — unless some of you cure bacon with java, which I don’t want to know about.
What the story (below) did was to try to present a cute little graphic summary of observational studies that show a statistical association between increasing coffee consumption and fewer early deaths, fewer deaths from heart attack, fewer cases of dementia, and fewer cases of type 2 diabetes.
But such observational studies (they actually never cite the source — I’m just giving them the benefit of the doubt that they’re citing observational studies) CAN’T establish cause and effect, therefore it’s inaccurate for the story to use terms like “cure,” “protective,” and “lowers (or reduces or slashes) your risk.” Besides being inaccurate, such stories fail to educate readers. They mislead.
We ask the editors of Prevention to read and understand our guide “Does the Language Fit the Evidence? Association versus Causation.”
*This blog post was originally published at Gary Schwitzer's HealthNewsReview Blog*
August 23rd, 2010 by GarySchwitzer in Better Health Network, Health Policy, News, Opinion, Quackery Exposed
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I’ve seen the very clever journalism warning labels pictured and offered on TomScott.com. Many good friends and contacts wrote me about this, some urging HealthNewsReview.org to produce its own — and we may. Of the many great labels offered, this one is perhaps my favorite:
*This blog post was originally published at Gary Schwitzer's HealthNewsReview Blog*
June 27th, 2010 by GarySchwitzer in Better Health Network, Health Policy, News, Opinion, Research, True Stories
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People aren’t dumb. Even if — or maybe especially if — news stories don’t point out the limitations of observational studies and the fact that they can’t establish cause-and-effect, many readers seem to get it.
Here are some of the online user comments in response to a CNN.com story that is headlined, “Coffee may cut risk for some cancers“:
* “I love how an article starts with something positive and then slowly becomes a little gloomy. So is it good or not? I’m still where I was with coffee, it’s all in moderation, it ain’t gonna solve your health woes.”
* “The statistics book in a class I’m taking uses coffee as an example of statistics run amuck. It seems coffee has caused all the cancers and cures them at the same time.” Read more »
*This blog post was originally published at Gary Schwitzer's HealthNewsReview Blog*
